Calculations of mean escape depths of photoelectrons in elemental solids excited by linearly polarized X-rays for high-energy photoelectron spectroscopy

Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

“…Additionally, the near-surface region of pyrite exhibits enhanced contents of S, polysulfide-type species and some monosulfide ions as compared to the FeS 2 composition. The thickness of this region is significantly lower than the measurement information depths of 10-15 nm [37,38], estimated at 1-2 nm for air-exposed pyrite and no greater than 3-4 nm for the ferric chloride etched mineral. Furthermore, there likely exists an extended region with insignificant compositional changes ("Fedepleted layer") beneath the "polysulfide" layer, at least, in the etched sample.…”

“…The results of the S 2p and Fe 2p band fitting are also presented as a function of excitation photon energy in Fig. 2, with approximate information depths [37][38][39][40][41][42]. Whereas the calculated O/S and C/S ratios rapidly fall with increasing photon energy, the Fe/S ratios are higher at an excitation energy of 2 keV but decrease to an approximately stoichiometric value of 0.5 (at 3 keV), at which it remains at higher excitation energies.…”

“…The spectra were acquired at photon energies from 2 keV to 6 keV and, in some cases, to 9 keV; the slit width was of 0.5 mm for all the excitation photon energies. Atomic ratios of elements (I i,h ) relative to S were calculated from the intensity area of the detail spectra for each energy (A i,h ) employing photoionization cross-sections ( i,h ) tabulated in [57,58] and the ones extrapolated for the higher energies, and taking into account IMFP ( (KE) i ) calculated for FeS 2 and Fe 9 S 10 employing TPP−2M formula [38] and analyzer's transmission function (T(KE) i ) [40][41][42] using following equation…”

“…Hard X-ray photoelectron spectroscopy (HAXPES) operates in the energy range of photons and emitted elec-trons of up to 10-15 keV with the IMFP approaching several tens of nanometers [36][37][38][39][40]. HAXPES is a non-destructive technique that allows to determine chemical shifts of core levels and chemical states of the atoms of interest at varying depths.…”

Thickness and coverage determination of multilayer with an island-like overlayer by hard X-ray photoelectron spectroscopy at multiple photon energies

“…Recently, hard X‐ray photoelectron spectroscopy (HAXPES), which commonly uses 6–15 keV X‐rays, has become one of the most powerful techniques for investigating the bulk electronic and chemical properties of solids . High‐energy photoelectrons, which are excited by hard X‐rays, possess a long inelastic mean free path (IMFP), leading to a deeper detection limit.…”